Micrometer and micrometric measuring instrument



p 1954 c. H. SEAHOLM MICROMETER AND MICROMETRIC MEASURING INSTRUMENT 3 Sheets-Sheet 1 Filed May 11 1950 q m mm INVENTOR. g (ix/mus 521m ATTORNEY Sept. 28, 1954 c. H. SEAHOLM MICROMETER AND MICROMETRIC MEASURING INSTRUMENT 3 Sheets-Sheet 2 E la .Q

INVENTOR. C'flfl/FLIS A Sim/0 M 4770/?NEY Sept. 28, 1954 c. H. SEAHOLM MICROMETER AND MICROMETRIC MEASURING INSTRUMENT Filed May 11, 1950 3 Sheets-Sheet 3 Patented Sept. 28, 1954 OF FICE "-MIOROMETE'R AND'M-ICROMETRIC "MEASURING INSTRUMENT Charles Seaholm, New York, N.JY.

Application May 11, 1950,-'SerialNo.' 161,303

2.3Claims. .11

.iFDhe :i'present' invention ':relates "to micrometers and \micrometric @measuring: instruments, .and: is ;more..; particularly :directed 1 to:.'such. instruments arranged fori'direot reading of extremely fine measurements.

SThe usual'micrometer used by machinists .and ztool-rmakers '..has :a scale .or scales 'which make zitrzpo'ssiblei to read directly to ma thousandth of ranfiinc'h ,(:001".).,iorr,0.0l ;mm., :andrto estimate dih 'sten'fuhousandths zof an; inch .'or "0.005 mm. LSuchxestimat-ingris conventionally accomplished rby'res'timatingi (guessing at 3.) diheposition 0f .the sleeve marking: relative to the barrel marking, :by -.thBiIISBTIDf*VBIIIiG1,-Z orL inc'some :other fashionsubgi'ectrto 51611101. v

:alocording :to Jtherpresent :invention, measuring .instrumentsiof various kinds .aand suited for various uses may be readily constructed vto give a direct thimbleqto barrel reading .of .0.0001 or f0e002zanm. withoutnany estimation whatever. o wernier or.;-'similar.:device is relied upon. :These .obiefctives -.:are.=accomplished by: producing the instrument :with (.1) iaz-spindle. normally locked against rotation :in :a-fixed barrel butzpresettable linrzspaced'apositionsshaving;regular steps (e. .g., 0.1"". sand ((-22) 21a thim'ble xsleeve :.;haying 2a differential Jthread: connection I with the fixed rbarrehoi ztheiinstrumentrand the-:non-rotatingspin- .dle. :.'I?he icpresetting 1.0f iithe .1 spindle :is accomzp'lishedsby releasing the lock; rotatingzthe spindle in rtheithreadedrsleevelarcomplete. :revolu'tion :or rasplurality; din-complete revo1utions,iafter which iitviiis' again locked againstnrotation. ?The.sthimble sleeve has a range of movement .sufiiciently great mo'qpropel' and repelt-he' spindle through a dis- :tance-ieqnalto the spacing of;successive-..positions (of the spindlasothatinsuch a range no spindle resetting is fnecessary. All measurements in the .range"(-e.gg.,-i0.'.l" to a0.2'.)-.'are amadeirom one spindle setting withoutithe' use of spacers, anvil resettingrzlevices and .the like.

measuring instrumentstmadeiraccording to the present invention, the spindle carries ex- .ternal-.threads at its inner concealed end and the-barreluof the instrument is provided with internal threads substantially greater in diamezterthan those :onethespindle and .having the difierential pitch relation. The threaded-end of the .-spin'dle.-.-is received in =aq-master or differeniti-alr sleeve :also threaded into the-:barrel. The 'sleeve carries :a thimble-adaptedto be secured to .itui'n adjusted ,position and extending along :the outsideiof the rbarrel.

Themicrometerbarrel-also carries two. readily accessible thumbgpieces, cone .?-for releasing I the 2 spindle flock and the other for operating a lock- .ing' spring which locks the thimbleand-threaded sleeve against rotation.

sfIlhe invention also contemplates an improved anvil .position indicator whereby it is possible .toomake certain-that the :measurement being made is always under a known anvil pressure. it sis'alsoipossible :to employ such mechanism with .a .manual release for peningand closing the *instrumentHwhen used as a comparator.

-:-Not only is "the invention suitable for embodiment .in a hand instrument, but it is also suitable for use -;in :many machines such :asjig borers, milling machines, etc., :where accurate positioning .of parts is of great importance. When so: employedtone can, with standard distan'cespieces "of precisely known length, :set the machinetokan accuracy of 0.0001" (or 0.002 mm.) by a direct reading instrument.

:Other-and further objects will appear as the description proceeds.

The accompanying :drawings show, for pur- :poses 10f illustrating. the :present invention, four embodiments in which thefiinvention may take :form, .it' being understood that the 'drawingsare illustrative of the invention rather than limit- .ing. the -same.

In these drawings:

Figure lris :an enlarged side elevational view .ofLa manually carriedand operated micrometer withg-parts-in section in the broken line ;l-.l =of Figure-.2, the .parts beingadjusted for :measuring awork'piece 0l999" thick;

:lEigureZzis a section on the line 2-2 of Fig- -ure .1 looking toithezright;

"Figure 3 iszan elevational viewof themicrometer with the spindle retracted and the thimble sleeve threaded. in;

Figure-4 is a sectional -view on'the line 6-4 of Figure 2;

Figure 5 is an elevational view of a "barrel extension sleeve, taken in the direction of the arrow 5, Figure '4;

Figure '6 is a section on the line 6-6 of Figures 4 and 5;

'Figure l6ais an enlarged fragmentary section on line EafEigure .6;

Figure 6b is a'fragmentary section on .line 6b otEigure 6a;

Figure '7 is -an.elevational view of the sleeve of Figur 5-taken from the right;

Figure '8 is a fragmentary elevational view :of the spring spreader;

"Figure 9 :isxan elevational'view showing the thimble sleeve friction spring detached and taken in the direction of arrow 5 of Figure 4;

Figures 10, 11 and 12 are fragmentary side elevational, top plan and sectional views of the base and movable table of a jig borer, milling machine or the like with attached micrometer;

Figures 13, 13a, 13b illustrate a measuring rod of standard or known length adapted for use with the micrometer of Figures to 12; and

Figure 14 illustrates a further modification.

Figures 1 to 9, inclusive, show an outside micrometer of generally C-shaped contour. The body or frame of the micrometer, designated generally at has a hollow cylindrical barrel 2| extending to the right in the drawings. erably made of tool steel. This barrel has at the left a smooth relatively small diameter cylindrical bore 22 which opens at the right into a larger diameter bore 23, and this in turn opens into a still larger bore 24 which extends to the extreme end 25 of the barrel. The body is drilled from the right end in the plane of the section of Figure 4 to provide a hole 23 extending nearly to the left face 21 of the barrel. Part of this drilling is cut away by the counterbore 24. Opposite the drilling 25 the barrel has an outwardly opening recess 28 which intersects the drilling.

The barrel is also drilled from the left face 2'! in the plane of Fig. 1 to provide aligned holes 29 and 90, the latter being of less diameter. A recess 3| intersects the drilling 29, 30. The drilling 29 carries a hardened bushing 32. A hardened pin or rod 33 guided in bushing 32 and hole is protracted by a spring 34 to project beyond the left face of the barrel. The pin or rod 33 may be retracted by a thumb piece 35 to bring the end of the pin into the bushing 32 and behind face 21.

The small diameter bore 22 of the barrel receives a pressed in tool steel bushing 36, expanded as indicated at 3? and carrying a twirling and controlling nut or collar formed of two parts 38 and 39 threaded together. The part 38 has a tapered drilling 38' to receive pin 35 and prevent turning when the pin is protracted. The part 39 has an opening with two parallel guide flats 40, 40.

The nut 39 receives a steel spindle 4| with corresponding flats 52, the front one of which carries indicia 42' (which in the English scale may be in and A of an inch, 1. e. 0.1, 0.05, 0.025), these extending to the left of the twirling nut 30, 39. The spindle has a Wear resistant tip 4! and its body is rotatably received in the bushing 35. It has a long threaded inner end 43, these threads in the English system ordinarily being threads per inch so that when the spindle 4i is turned by the collar one revolution in a stationary threaded member, the spindle 4| moves one division or 0.025. The collar 38 has a conveniently located registry line 38y coinciding with line 382 on the frame when locking pin 33 is in line with recess 39'.

The counterbore 2d at the right of the barrel 2| receives a sleeve 44 (Figs. 5-7), which in effect provides an extension of the barrel. The sleeve 44 has a light press fit, a shoulder 45 engages the end 25 of the barrel and its end 45 engages the reducing shoulder between bores 23 and 24. It is pinned in place by a taper pin 41. It has a groove at 48 in line with the hole 26. It has a collar 49 spaced from the shoulder 45 and cut away at 59' in line with groove 53 and at 49" at the opposite side. Sleeve 44 is slitted as shown at and provided with tapered threads 5|. The slits preferably do not come all the way to the It is prefend of the sleeve at its inner diameter. The sleeve 44 is internally threaded as shown at 52. These threads bear a difierential relation to the threads 43 on the spindle and in the English system would be 40 %1 or 36 threads per inch.

The male thread 43 on the spindle 4| and the female thread 52 in the barrel extension sleeve 44, receive a master or differential sleeve 55, preferably Phosphor bronze, with male and female threads 56 and 5'! cooperative with the same, and at the outer end is provided with a head 55 threaded at 59. Vent holes are drilled at 55a and 55b. An outer sleeve 60 is secured on the master sleeve and extends leftwardly and about the outside of the barrel 2| and extension sleeve 44 so as to cover and protect these parts and make it possible to read the relative angular and longitudinal positions of the sleeve 50 and the barrel 2|.

The master or differential sleeve 55 as well as the outer sleeve 60 are kept from turning whenever desired by an arcuate, preferably Phosphor bronze friction spring 6| (Figs. l, 6 and 9), received in the space between collar 49 and the end 25 of the barrel proper, and when expanded adapted to engage the inner wall of sleeve 60. The mid portion 6|a of the spring is received in slot 49" of sleeve nut 44. The ends of this spring are beveled as indicated at 62 (Fig. 9) and receive the wedge shaped end 63 of a rod or pin 64 which extends through the drilling 20, lengthwise through the recess 28 and through the thumb piece 65 to which it is secured. When this thumb 'piece is in the position shown in Figure 4, the spring grips sleeve 44 and is, as shown in Figure 612, out of contact with the thimble, so that it can be turned, but when the thumb piece 65 is shifted to the left, the thimble is gripped and the sleeve 55 locked.

The stationary body of the instrument carries lineally arranged graduations 66 which spread over a distance of 1.1000", and in the English system read 0.0025, 0.0050", 0.0075", 0.0100, etc., up to 0.100". The left end of the outer thimble sleeve 60 is tapered to a thin edge as indicated at 61 and carries peripherally arranged graduations, indicated at 68. It takes 40 revolutions of the sleeve 55, 60 to shift the spindle 0.1 and make the sleeve travel the 1.1000" dis tance included between 0.0 and 0.1 on scale 66. The spacing from 0.0000 to 0.0025 on scale 66 is actually 0.0275 and equals the difierential movement produced by one rotation of the thimble sleeve 55, 60, hence it is possible to read each 0.0001" directly.

The micrometer reading for the setting shown in Figure 1 is obtained by observing that thimble sleeve 60 has been turned beyond the zero line so that 0.0024" is opposite the center line of scale 66. Thus, 0.0975", plus the thimble barrel reading of 0.0024 gives 0.0999". This, added to the previously established gap of one-tenth of an inch obtained when the spindle was set to span the distance 0.1 to 0.2 on the scale 42, makes the complete reading 0.1999", which, it will be noted, is accomplished without any estimation, Vernier or the like. In practice, the user would read the instrument zero point one nine seventy-five plus twenty-four or zero one nine-nine-nine.

The threads 52 on the sleeve 44 and 56 on the sleeve 55 are subject to wear. While the parts are replaceable, their useful life may be prolonged by adjusting for wear by means of tapered nut '10 carried on threads 5| on sleeve 44. This nut 10 is accessible when outer sleeve 50 is removed. To make it possible to adjust for the effect of wear is fixedly secured with its axis horizontal, this body is provided with the same functioning parts as the right-hand portion of the body 20 of the form shown in Figures 1-9, and carries the same parts, differently arranged to facilitate their use alongside the machine body.

The body N35 has a longer barrel I06 and the spindle setting thumb piece 35a and thimble locking thumb piece 65a may be aligned near the top of the barrel. The twirlin nuts 38a, 39a are arranged to be stopped so that the flats 42a on the spindle dla are horizontal. The scales 66a and 662) are on top of the barrel Iilfi and of the thimble Gila. The readings refer to such a scale.

The spindle Ala extends beyond the scale so as to carry a dial indicator I01 secured to it by clamping bolts I68 and a slidable spindle exten- $1011 569. The spindle extension is urged to the left by a cushioning spring H) received in a counterbore HI in the spindle extension and its movement is limited by bolts H2 which pass through clearance holes in the dial indicator structure. The slidable spindle extension bears against the plunger till of the dial indicator and has vertical flats I I3 and a contact face H4.

The movable work table Hi2 of the machine carries an anvil supporting bracket H5 secured in place in any convenient manner, as for example by bolts I I5. The bracket has a horizontally threaded bore II'I aligned with the bore of the micrometer body 95 and carries an adjustment screw H8, having an anvil face H9 and adapted to be clamped in place by a constricting screw I20.

The contact faces of the spindle extension and of the anvil are preferably wear resistant. Where the movable table is located so that the distance separating these faces is within the reach of the micrometer, measurement may be made directly (as shown in Fig. 11) without any auxiliary spacers. Where, however, the spacing is greater, standard spacers, made to known lengths may be employed. Such a spacer is indicated in the drawings at [2 I. To facilitate holding it in place, it carries sleeves I22 and I23 slotted as indicated at I24 and I25 to fit over the anvil member HS and the flats H3 on the spindl extension we. The flats H3, I25 prevent any rolling movement of the spacer rod.

In the embodiment of the invention pictured in Figures to 13, the non-rotative spindle carries the pre-set indicator, cooperating with the spindles pushed-out contact surface. This spindle extension me would, like the floating anvil of the micrometer already discussed, require a pushing back of approximately one to two thousandths of an inch in order to exhibit the true reading, disclosed when the indicator hand registers zero. Hence, the projected over-reach of the spring- (or otherwise)cushioned contact end I I4 being in this case absorbed into the indicator mechanism as contact is made, the anvil proper, or the abutting end of the rod from which the measure is reckoned, is fixed, i. e., non-cushioned. While the dial indicator I0! is of conventional contour, I do not limit myself to any particular shape or location of the indicator for the attainment of the aim of a double-check reading. The body of this auxiliary registering device may be that of a thin disc, or it may be cylindrical, annular, saddle-shaped, or of any other convenient form; it may also be placed farther back from the contact end of the spindle than shown as long as. it truly records, through physical connection, the absorption of the movement of the spindles cushioned contact end requisite for a double-check of the basic setting of the spindle and the thimble-to-barrel reading of the micrometer. Also, the indicators registering marker may oscillate over a flat dial, or over a peripheral or truncated conical dial, or it may travel reciprocally-axially.

In this embodiment the range of the instruments usefulness is extended to the machine tool field proper. By means of selective settings of the contact elements afforded by an appropriately placed T slot system, as shown in Figures 10 to 12, and the use of measuring rods of varying lengths, and the length increment from rod to rod being in agreement with the capacity of the micrometer, the correct gauging of machine tool table movements becomes relatively easy. The adaptation may be made by adding the T slot arrangement to machine tools already in use, such as jig borers, milling machines, precision lathes, etc., or by incorporating in the patterns and castings the features requisite for integrating the instrument with new machine tools being built. It being exceedingly difficult to produce and maintain accurate machine lead screws of considerable length, the invention will be found valuable in the applications referred to, and in many similar applications, since the accurate length of each spacer rod is readily attainable. Tipping the ends of the rods with wear resistant material such as tungsten carbide, or the like, will insure continued precision and dependability of these members. The linear extent of the T slot scheme being suited to the machine of flxture to which it is applied, and the spacer rod increments being commensurate with the range of the micrometer spindle, it follows that any setting within the limits of the machines table travel, or limit of tool travel, may be had with ease and exactness.

It is apparent that the devices shown in Figures 10-13 may also be used generally in machines where measurements of great accuracy are to be made whether lengthwise of the machine bed, crosswise of it, or vertically, the parts being mounted in optimum positions for use.

In Figure 14, the body I50 of the micrometer has a cylindrical bore I5I which receives the spindle 552 similar to the spindle of Figures i-1l. The body has flattened sides I53, I53 which intersect the bore. They are spaced the same as the flattened sides I54 of the spindle so that the spindle sides are exposed. The body has a slot I55 below the bore. A spacer $56 is received in this slot and is secured by screws l5l to jaws lEB, I59 which engage the side faces of the body. When the jaws are in the position shown in the drawing, the spindle is held against rotation, but can be moved by the thimble sleeve as above described. When the jaws are lowered, the spindle is free for rotation and adjustment as above de scribed. This spindle lock may be used instead of the twirling nut.

Since it is obvious that the invention may be embodied in other forms and constructions within the scope of the claims, I wish it to be understood that the particular forms shown are but two of these forms, and various modifications and changes being possible, I do not otherwise limit myself in any way with respect thereto.

What is claimed is:

1. A micrometer having a tubular body provided at its inner end with a fixed sleeve forming a spindle bearing, with cylindrical bearing surmemorie- 9 race and a; flanged? extension: spaeed the body; a spindle: slid'ably and": rotatablwmcnmteth inrtheibearing;two-collars threadedztoeether 'andi rotatable: aboutthe flange; one colla'r havingh'as non circularr opening and therspindlerhaving: a" mini-circular: pnrtion fitting: the nomcircwler: o ening: the spindle :beiir atlireaded at its remote: on outer 'endiiandi carryingronisitsfprotrnding indieia: spaced according: to the pitch on the? oithe: barrel, protruding: beyond: the 'barrel ahd r extending; about the: outer end i of: the: barrel 'andi provided: with: internal: threads: of; differentialv piteh, atthiinble carried by: the: thirho'l'e sleeve;, at spindile bearlng sleeve secured in: thebore: a'i

threads on the outer end, the outer end ofrthei 1'0 splndlei liavinglitsi outer'end: threaded: intoz ther bodyzbeing internally threadedratfaipitcmdifierent from that 1 of: the spindl'e threadsg laathimbleesleeve' threaded. into?" the body-"and onto the spin'dIe so: thatrlengthwisei movementrofithel thimblersleeve threadedisleevez andi its inner end carried in: the spindlervbearingia sleeveand protrudings'beyond it, thei'inneri end iofi therspindler having: a fi'attened sid'efiproviding; an elongated iindicia bearingvareag anditheilo'cked spindlehavefairaticflcorresponding? 1'5-1 as spindle: twirling: device rotatably. andnon to: the thread: pitch ratios; cooperabler fixedisandi rotatable: spindles locking: meanss wli'lchi: wliemim unlockedi position permitsirotation oifiltheifspindle and:dongitudinal-ediustment thereofiin thezthimi removably carried by therinner'end o'fithe-JbearJ-- in'gi'sleevefiarrd engaging-whet flattened: side: of 5 the spindle: so: that: whom the: spindle is' rotated." by the twirlingrdevice-Ithe spindle isrshifted length-- ble cylinder 'tiireads whenzlocked holdsfi the; wiseymeansto lock"v twirling v devioein one:

spindle: in: a, selected angular position; and a thimbleIcarried-by the thimbleisleevesandiextendk ing: inwardly. about: the: outers'endi of: the: body; the: body andixthimblei sleevezhaviirgx cooperative angular'positionl onlitstmfixrthei angular position oi 'thei spindle; the spindle side having. indicia spaced according: to" thepitchv oh the: spindle: threaflsatheendmilthe thimble carrying circumindiciaareadable 'in accordance with the long-1 ferentially: arrangedi indicia; the. barrel carryingi tudinal'iandi angular: positions ofl the thimblezandi in: conjunction with. the: indioiaz on the: spindle? indieati-ng the: position of the spindle relative to thelmicrometen-bodyt 25 Ar micrometer: as: olaimechimclazinn- Lhwliere inxthe ratio of that differential threads orrlth'ei: sleeve: is? such". that al multiple: integral number: of revolution's of tliefi-tliin'lbleEsleeverahd thimble sheets the same movement of? the spindle ais one; revolution of the spindle whereby (2116 thimble=body 'indici'a' cover: a; range equaI: toithat: ofonerevolution' of the spindle.-

3;: Aimicrometor a's claimed in claini 1; wherein: the spindle has-Y5 threads per-unit of leng-th and the body has threads per unit length; m" and. being whole numbers andww l'essthan 11;.

4: A micrometer as 'iclaimedin' claiinl wherein the spindle: and thimble'sleeve" have qdtlire'adn per: inch and .the' spin'dl'ehas=graililationsspao'ed .0250 and the body? and" thimb'i'e sleeve? have 36%1 threads "peninch; the'"longltudinal tiiimbl'ef U sleeve-to-b'ody" indi'cia; beingIspaceIi" .0250' X /ii or .0275 for each. revolution of the. tfiiinbl" sleeve, the cylindrically disposed in'dieiaomtlie thiinble sleeve being spaced evenly to permit reading fractibnahparlfs ofa: revoliitiont.

5; A micrometer-asclaimed iir'claiin1 where" ih'th'etubular body ism'ade'intwdpartnonepartt being 'counterbore'dto receiveth'e redueeuend of thetapered counterbureawlierebwthe spihdlemaw be expanded to 'c'omp'enssat-tenor wear;

longitudinally extending indiciai past: Which the: end ofzth'e thim'ble moves,' said -1atter\ mentioned indicialhaving a' spaoial relationship :relative: to

thosei onithex'spindlel: corresponding withrthe difi- 3'0? ferential: relatiomoflthe?threads;

ber adapted to7 be held: stationary: or: turned-son:

1 its: axis and atspindleibearing member in. which:

thelspindler isi freely rotatable and:longitudinallyr 4t)?- spindl'ei extendshthersecond collar havingalcor respondingly" shaped opening-cs0 that 1311630011213 when turned. about the: spindle. axis: turn. the? spindle: andi shift iti in the. threaded v spindle: re.- ceiving member; andi means to lock' the" collars o againsttrotation soithatthezspindle maybezlock'ed against; rotary? movements without interfering- 1 with itsl longitudinal movement: when the." threaded spindles-receiving: member isiturn'edz lflnlm at micrometer; as: claimed in claimi 9;.v

-\ whe'xeinathe loclringlmeans:includes alspring-lproetraete'd; manually retractable :plimger carried: by the bodyIandI-a reeess inlthe-lfirst thnaadeoi:ring to 'receive the protraoted plunger.

contracted, split, annular spring, anda bodycarried', slidable wedge between the ends of i the spring; and a -means toshiftthe=wedgeback anw forth- 1'22 Ina micrometer, a body having" an' nular sprihg receiving channel nea'r its=outen end; a= split annular' spring received in thechannel" andilo'ek ed opposite the split against rotation; a longitudinally extending; body" carriedrod hav-- in'g a we'dge-shaped spring exp'ahdenb'etween the 1 sleeve and' extending-ont'side the body and 0p-' p'o'site the spring; thesprin'g when contractd being-1 free of the thimble: and:- when: ex 'anded frietionally engaging the :bo'dy-J manna: micrometer; a bodyh'avine" a" spindle" hearing at one end and counterbo'red' at ailarger diameter at the other end, an interally threaded extension sleeve fitted into the counterbored end and non-rotatably secured therein, the extension sleeve having a shoulder spaced from the end of the body to provide annular space, the shoulder being cut away at two opposite places, an annular contractible spring having an anchorage lug on one shoulder cut out and free ends aligned with the other cut out, a longitudinally extending drilling in the extension sleeve and body in line with the ends of the spring, a rod slidably carried in the drilling and having a wedge-shaped end between the spring ends for expanding the spring to grip a thimble, and a thimble about the extension sleeve and body and threadedly supported from the extension sleeve.

14. In a micrometer, a thimble sleeve having internal threads adapted to carry a spindle and external threads of different pitch adapted to be received in a micrometer body, the thimble sleeve having a closed end provided with a collar, a reducing shoulder and a threaded boss, a thimble slidably received by the collar and having a flange fitting against the reducing shoulder, and a nut threaded on the boss and bearing against the flange on the thimble.

15. A micrometer having a tubular body provided at its inner end with a spindle bearing, a spindle slidably and rotatably mounted in the bearing including a cylindrical bore with two cut-- away portions, the spindle having a non-circular portion and being threaded at its remote or outer end and carrying on its protruding end indicia spaced according to the pitch of the threads on the outer end, the outer end of the body being internally threaded at a pitch different from that of the spindle threads, a thimble sleeve threaded into the body and onto the spindle so that lengthwise movement of the thimble sleeve and the locked spindle have a ratio corresponding to thread pitch ratios, cooperable fixed and rotatable spindle locking means which when in unlocked position permits rotation of the spindle and longitudinal adjustment thereof in the thimble cylinder threads when locked holds the spindle in a selected angular position, a thimble carried by the thimble sleeve and extending inwardly about the outer end of the body, the body and thimble sleeve having cooperative indicia readable in accordance with the longitudinal and angular positions of the thimble and in conjunction with the indicia on the spindle indicating the position of the spindle relative to the micrometer body, and a pair of slidable jaws in said cut-away portions of the spindle and shiftable from a position where they engage the spindle to prevent rotation to a position where they are free of the spindle so that it may be rotated.

16. A micrometer having a tubular body provided at its inner end with a spindle bearing, a spindle slidably and rotatably mounted in the bearing, the spindle being threaded at its remote or outer end and having a flat sided protruding end carrying indicia spaced according to the pitch of the threads on the outer end, the outer end of the body being internally threaded at a pitch difierent from that of the spindle threads, a thimble sleeve threaded into the body and onto the spindle so that lengthwise movement of the thimble sleeve and the locked spindle have a ratio corresponding to thread pitch ratios, cooperable fixed and rotatable spindle side engageable, spindle locking means which when in unlocked position permits rotation of the spindle and longitudinal adjustment thereof in the thimble cylinder threads and when locked holds the spindle in a selected angular position, and a thimble carried by the thimble sleeve and extending inwardly about the outer end of the body, the body and thimble sleeve having cooperative indicia readable in accordance with the longitudinal and angular positions of the thimble and in conjunction With the indicia on the spindle indicating the position of the spindle relative to the micrometer body.

17. A micrometer having a tubular body provided at its inner end with a spindle bearing, a spindle slidably and rotatably mounted in the bearing, the spindle being threaded at its remote or outer end and carrying on its protruding end indicia spaced according to the pitch of the threads on the outer end, the outer end of the body being internally threaded at a pitch different from that of spindle threads, a thimble sleeve threaded into the body and onto the spindle so that lengthwise movement of the thimble sleeve and the locked spindle have a ratio corresponding to thread pitch ratios, cooperable fixed and rotatable spindle locking means including a longitudinally slidable plunger and a revolvable nut provided with a stop engageable with the plunger and having a fixed angular relation with the spindle, said locking means acting when in unlocked position to permit rotation of the spindle and longitudinal adjustment thereof in the thimble cylinder threads and when in locked position to hold the spindle in a selected angular position, and a thimble carried by the thimble sleeve and extending inwardly about the outer end of the body, the body and thimble sleeve having cooperative indicia readable in accordance with the longitudinal and angular positions of the thimble and in conjunction with the indicia on the spindle indicating the position of the spindle relative to the micrometer body.

18. A micrometer having a tubular body provided at its inner end with a spindle bearing, a spindle slidably and rotatably mounted in the bearing, the spindle being threaded at its remote or outer end and carrying on its protruding end indicia spaced according to the pitch of the threads on the outer end, the outer end of the body being internally threaded at a pitch diii'erent from that of the spindle threads, a thimble sleeve threaded into the body and onto the spindle so that lengthwise movement of the thimble sleeve and the locked spindle have a ratio corresponding to thread pitch ratios, cooperable fixed and rotatable spindle locking means which when in unlocked position permits rotation of the spindle and longitudinal adjustment thereof in the thimble cylinder threads and when locked holds the spindle in a selected angular position, a thimble carried by the thimble sleeve and extending inwardly about the outer end of the body, the body and thimble sleeve having cooperative indicia readable in accordance with the longitudinal and angular positions of the thimble and in conjunction with the indicia on the spindle indicating the position of the spindle relative to the micrometer. body, and means to lock the thimble and the thimble sleeve against rotation so that the spindle may be turned in the bearing and thimble sleeve threads.

19. A micrometer having a tubular body provided at its inner end with a spindle bearing, a spindle slidably and rotatably mounted in the bearing, the spindle being threaded at its remote or outer end and carrying on its protruding end indicia spaced according tothe pitch of the threads-Lon the outer end,-;,.th'e2 outer endiaofcth'e body being internally threadedr at a pitch" different from that of the spindle threads, acthimble sleevethreaded into. the body: and. onto the spindle sothat lengthwisermovement of the thimble sleeve. and the locked-spindle: havera ratio. corresponding to thread, pitch ratios,. cooperable fixed and rotatable spindle locking means which when in unlocked position permits-rotation of the spindle' and longitudinal adjustment thereof in the thimble cylinder threads and when lockedholds the spindle ina-selected angular position, a thimble-carried by-the'thimble sleeve and extending inwardly about the outer end of the body, the body and thimble sleeve having cooperative indicia readable in accordance with the longitudinal and angular positions of the thimble and in conjunction with the indicia on the spindle indicating the position of the spindle relative to the micrometer body, a normally contracted spring carried by the body inside the thimble sleeve, and cam means for expanding the spring to cause it to grip the thimble and prevent turning of the thimble and thimble sleeve.

20. A micrometer having a tubular body provided at its inner end with a spindle bearing, a spindle slidably and rotatably mounted in the bearing, the spindle being threaded at its remote or outer end and carrying on its protruding end indicia spaced according to the pitch of the threads on the outer end, the outer end of the body being internally threaded at a pitch different from that of the spindle threads, a thimble sleeve threaded into the body and onto the spindle so that lengthwise movement of the thimble sleeve and the locked spindle have a ratio corresponding to thread'pitch ratios, cooperable fixed and rotatable spindle locking means which when in unlocked position permits rotation of the spindle and longitudinal adjustment thereof in the thimble cylinder threads and when locked holds the spindle in a selected angular position, a thimble carried by the thimble sleeve and extending inwardly about the outer end of the body, the body and thimble sleeve having cooperative indicia readable in accordance with the longitudinal and angular positions of the thimble and in conjunction with the indicia on the spindle indicating the position of the spindle relative to the micrometer body, a longitudinally reciprocable, body-carried rod with an externally accessible thumb piece and a wedge shaped cam near the outer end of the body, and a normally contracted spring carried by the body inside the thimble and engageable by the wedge shaped cam to be expanded thereby against the inner surface of the thimble sleeve.

21. A micrometer having a tubular body made of two parts threaded together and provided at its inner end with a spindle bearing, a spindle slidably and rotatably mounted in the bearing, the spindle being threaded at its remote or outer end and carrying on its protruding end indicia spaced according to the pitch of the threads on the outer end, the outer end of the body being internally threaded at a pitch difierent from that of the spindle threads, a thimble sleeve threaded into the body and onto the spindle so that lengthwise movement of the thimble sleeve and the locked spindle have a ratio corresponding to thread pitch ratios, cooperable fixed and rotatable spindle locking means which when in unlocked position permits rotation of the spindle and longitudinal adjustment thereof in the thimble cylinder threads and when locked holds the spindle in% a selected angular-position, a: thimble carried by the thimblesleevena'nd extendi1'ig fi'n-v wardly about the outer. end. of: the bodypar nor-- mally contracted spring inside the thimble. and non-rotatably carried by thethreaded body part;

the body: and thimble sleeve having. cooperative:

indicia readable in accordanceiwiththe'longitue dinal and angular positions of the thimble and in conjunction with the indicia-- on-the"spindle indicating:' th ez-ppsitioni'iofxthe spindlearelative to the micrometer body, the two. body parts being longitudinally drilled, a slidabl'e spring expander in. the drilling, and a thumb piece for actuating the spring expander back and" forth to lock or unlock the thimble.

22. A micrometer having a tubular body provided at its inner end with a spindle bearing, a spindle slidably and rotatably mounted in the bearing, the spindle being threaded at its remote or outer end and carrying on its protruding end indicia spaced according to the pitch of the threads on the outer end, the outer end of the body being internally threaded at a pitch different from that of the spindle threads, a thimble sleeve threaded into the body and onto the spindle so that lengthwise movement of the thimble sleeve and the locked spindle have a ratio corresponding to thread pitch ratios, cooperable fixed and rotatable spindle locking means which when in unlocked position permits rotation of the spindle and longitudinal adjustment thereof in the thimble cylinder threads and when locked holds the spindle in a selected angular position, a thimble carried by the thimble sleeve and extending inwardly about the outer end of the body, the body and thimble sleeve having cooperative indicia readable in accordance with the longitudinal and angular positions of the thimble and in conjunction with the indicia on the spindle indicating the position of the spindle relative to the micrometer body, the thimble sleeve having a closed outer end with a reducing shoulder and protruding threaded boss, the thimble having an inwardly flanged outer end bearing against the shoulder on the thimble sleeve, and a nut threaded on the boss for securing the thimble and thimble sleeve together.

23. A micrometer having a tubular body provided at its inner end with a spindle bearing, a spindle slidably and rotatably mounted in the bearing, the spindle being threaded at its remote or outer end and carrying on its protruding end indicia spaced according to the pitch of the threads on the outer end, the outer end of the body being internally threaded at a pitch different from that of the spindle threads, a thimble sleeve threaded into the body and onto the spindle so that lengthwise movement of the thimble sleeve and the locked spindle have a ratio corresponding to thread pitch ratios, cooperable fixed and rotatable spindle locking means including a longitudinally slidable plunger and a revolvalole nut provided with a stop engageable with the plunger and having a fixed angular relation with the spindle, and acting when in unlocked position to permit rotation of the spindle and longitudinal adjustment thereof in the thimble cylinder threads and when in locked position to hold the spindle in a selected angular position, a thimble carried by the thimble sleeve and extending inwardly about the outer end of the body, the body and thimble sleeve having 00- operative indicia readable in accordance with the longitudinal and angular positions of the thimble and in conjunction with the indicia on the spindle indicating the position of the spindle relative to the micrometer body, and means to lock the thimble and thimble sleeve against rotation so that the spindle may be turned in the bearing and thimble sleeve, the thimble locking means being angularly displaced from the spindle locking plunger.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 626,876 Spalding et a1. June 13, 1899 679,779 Pierpont Aug. 6, 1901 Number Name Date Starrett July 20, 1909 May Mar. 30, 1915 Gribble May 11, 1948 Sachtleber Apr. 19, 1949 Brown Sept, 12, 1950 FOREIGN PATENTS Country Date Great Britain 1900 Great Britain 1906 Germany Oct. 31, 1924 Great Britain Jan. 30, 1948 

